The objective of this proposal is to create a high-throughput, low-cost system for predicting the success of antiviral treatment of individuals infected by Human Immunodeficiency Virus (HIV). The core of our approach is the Invader assay, a linear signal amplification method suitable for point mutation detection, even of low-level minority alleles in mixed populations. The Invader assay's high specificity, achieved through the combined power of allele specific hybridization and structure-specific enzymatic recognition, permits the detection of HIV drug resistance mutations present as only a small fraction (less than 0.1%) of the total population. In Phase II, we propose to develop an integrated, low-cost HIV genotyping platform to detect all established mutations affecting resistance to antiviral therapy. We will adapt the pilot assay to a microtiter plate-based format which we will validate on clinical samples obtained from Stanford University. This system will be highly accurate for the detection of the critical and secondary mutations leading to reduced susceptibility to the front-line antiviral agents currently FDA-approved in the U.S. The major impact of this innovation will be its ability to predict the success of individual treatment regimens through the detection of early emergent alleles leading to drug resistance. PROPOSED COMMERCIAL APPLICATION: Marketing surveys indicate a potential market of $270 million for nucleic acid-based HIV genotyping due to the high incidence 6f resistance and the side effects associated with anti-viral treatments. While the clinical impact of early detection of drug resistance mutations has not yet been demonstrated, since it has been beyond the capabilities of existing technologies, a low-cost assay with the ability to detect low levels of these mutations has the potential to be of enormous value in predicting patient response.